What I have found to work best is to 1) avoid the temptation to level the ruts and leave them be until it is dry and then level it and 2) try to stay off it the first spring after leveling.  It takes a couple years, but every year the ruts are shallower and shallower.  Every time you disturb the drive it takes a freeze/thaw cycle to get everything to set up.  You can put down 12" of gravel, pack it, and the following spring drive a semi on it and leave 8" ruts, but if you can discipline yourself to stay off it for the first spring the following spring your ruts will be under a half inch.